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STUDIES IN
SMALL-POX AND VACCINATION

WILLIAM HANNA, M.A., M.D., D.P.H.

Assistant Medical Officer of Health for the Port of Liverpool ;
Visiting Physician to the Port Isolation Hospital.

NEW YORK:
WILLIAM WOOD AND COMPANY.

MDCCCCXIII.

^■

PREFACE

The following studies on the subject of small-pox and its
prophylaxis by vaccination have been the outcome of
several years of observation of cases which have occurred
in the City and Port of Liverpool. Ample opportunity
has been afforded for this study from- the unique position
of Liverpool as a shipping centre, and tlie great tide of
alien traffic which flows through it.

The first and second parts deal with the ever-important
problem of the value of vaccination in preventing and
mitigating attacks of this dreaded malady, and the inverse
relationship of scar-area to severity of attack is pointed out.

The final portion treats of " Concurrent Small-pox
and Vaccination " : a very interesting and important
subject.

It is hoped that the book will appeal to Medical
Officers of Health, Vaccination Officers, and those in cliarge
of Infectious Disease Hospitals. In addition, general
practitioners may find it useful in furnishing illustrations
of cases of smaU-pox. The work also contains useful
and striking diagrams and arguments as to the value of
vaccination and re-vaccination which may be used
with parents and others who object to these preventive
operations.

I am indebted to Dr. E. W. Hope, Medical Officer of
Health, City and Port of Liverpool, for much valuable
criticism, and to Dr. N. E. Roberts, Visiting Physician,
Liverpool City Hospitals, for the loan of some photo-
graphs which have enabled me to complete my series
illustrating the various points in the text.

Liverpool, W. HANNA.

February, 1913.

281496

CONTENTS

PAGES

Introduction ....... 7-10

Part I. — A Statistical Study of 1,163 Cases of Small-pox,
WITH Special Reference to Vaccination in Modifying
THE Disease ...... 11-26

Part II. — An Analysis of 943 Cases of Small-pox (with
Primary Vaccination) in Relation to Scar-area and
Severity of Disease .... 27-34

Part III. — Observations on the Interaction of Concurrent

Variola and Vaccinia ..... 35-49

Conclusions . . . . ... 51

STUDIES IN
SMALL-POX AND VACCINATION

INTRODUCTION.

A STUDY of the early history of small-pox, before vac-
cination was introduced, shows that the disease was one of
extensive prevalence and great malignancy. In the i8th
century it reached its highest point of intensity and dis-
tribution in Europe, the mortality from smaU-pox in
England at that period being one-tenth of the total
mortality. In London it was constantly present, and the
deaths averaged, during the period 1761-1796, from
3,000 to 15,000 yearly ; indeed, in the latter half of the
century the deaths seldom fell below 1,000. The great
mahgnancy of the disease when introduced into fresh
countries in later years has also been frequently recorded.
The decrease in smaU-pox prevalence since the beginning
Lol the 19th century, and the marked reduction in its
I fatality, have been shown to be due to the protection
afforded by the process of vaccination.

There is no subject of medical or scientific interest
which has given rise to such controversy as that of the
value of vaccination. In the early days of its introduction,
Jenner did not stand alone, for Woodville and Pearson,
physicians to the SmaU-pox Hospital in London, made
numerous experiments and came to the same conclusion

as Jenner, that the process conferred protection against
small-pox. The systematic observations of many quali-
fied observers have, however, long since turned the tide
in favour of the upholders of the practice as a scientific
and prophylactic measure, and it is unnecessary now to
draw attention to the convincing figures which have
proved its value. It is sufficient to state that from a
long study of the pock diseases of animals, especially vac-
cinia or cow-pox, and from experiments and observations
made by scientists, the relationship of variola and vaccinia
has now been established on a firm basis of fact. The
experiments of such observers as Thiele, Ceely, King and
Hime, and more recently of Klein and Copeman, have
shown that it is possible to inoculate a calf with small-pox
material and to obtain a vesicle at or near the site of
inoculation, identical, or almost so in the first instance,
with a human vaccine vesicle. This vesicle becomes even
more typical in the case of successive inoculations, and the
result is practically the same as if the animal had been
inoculated with vaccinia, for the calf is no longer susceptible
to vaccination. In addition, the lymph from these vesicles
has been transferred and used to inoculate successfully
human individuals, and the attenuated virus confers
protection against human small-pox as ordinary vac-
cination does.

( Small-pox still continues to invade our shores from
abroad, the extensive movements of populations, the
rapid means of communication, and the travelling
facilities afforded by fast steamships, enabling the disease
to jeopardize our ports and the country generally, even
more so than heretofore. Countries such as Canada, the
United States of America, Spain, Russia, Egypt, etc., are
well within the incubation period of the disease, and from

time to time persons have been landed in our ports in the
incubation stage.

In the interval after a great epidemic, material will
gradually accumulate in the shape of large numbers of
susceptible children in districts where primary vaccination
has not been carried out with strictness, e.g., in the London
Metropolitan Unions, where the number of children not
finally accounted for (including cases postponed and for
which "certificates of exemption" were granted) per cent
of total births in the respective years was as follows : —

1893-97 - - - 23-9 %

1899-1906 - - - 23-5 %

1907 - - - - 25-8 %

1908 - - - - 28-8 %

1909 - - - - 307 %

It will thus be seen that, just before an epidemic, a
large proportion of children in some large towns may be
unprotected by vaccination. In Liverpool the percentage
not finally accounted for is comparatively small, being
about 5 per cent. Again, those who have escaped the
epidemic owing to good vaccination lose some of this
immunity as years pass, or in the words of the late Dr.
Bond, of Gloucester, " become de- vaccinated " and so
provide suitable material for the next outbreak, when the
virulence of the disease may succeed in breaking down a
comparative insusceptibility.

The liability of a population to a small-pox epidemic
therefore ma}' be measured by its density at susceptible
ages.

After a long spell (seven years) of comparative quies-
cence, the disease broke out in epidemic form in Britain
in 1902-3 ; it carried off a large number of persons ; in

the City of Li\'erpool alone there were during that period
2,280 cases, with 161 deaths.

This epidemic of small-pox was extensively prevalent
in Europe and America, and tlie first Liverpool cases
were introduced amongst cattle-men from Boston, U.S.A.
The disease was raging in Boston, and many cattle-men,
employed on cattle boats from the United States, landed
in Liverpool ; these men were frequently incubating
small-pox, and subsequently developed symptoms of the
disease in the various lodging-houses of the citj^ These
foci helped on the gradual evolution of the epidemic which
was extending over the country. London and other large
centres became infected about the same time. In London
the disease originated in a Pole, residing in Stepney, who
had returned from a visit to Paris ; subsequent importa-
tions came from Egypt and elsewhere.

The series of small-pox cases under consideration has
been collected from amongst those which have been
admitted to the hospitals of the City and Port of Liverpool
during the past ten years. The large majority occurred
during the above-mentioned epidemic period (1902-3), and
since then the cases admitted have been chiefly imported
from abroad.

All the cases which occurred during the epidemic
were not available for the purposes of this investigation,
owing to the fact that the method of recording the required
particulars was not at first adopted.

PART I.

A STATISTICAL STUDY OF 1,163 CASES OF SMALL-POX,

WITH SPECIAL REFERENCE TO VACCINATION

IN MODIFYING THE DISEASE.

The examination of a large series of cases of small-pox is
of value as affording additional testimony to the effiicacy
of vaccination as a prophylactic measure, as an estimate
of the severity of the disease, and of the mortality gener-
ally in the vaccinated and unvaccinated ; and in particular,
the measure of the efficiency of the vaccination in the case
of the vaccinated. Some new methods have been adopted
in recording and comparing this series of cases.

It has been noted from time to time in vaccination
records, e.g., those of Russell, Marson, Gayton, and others,
that the quality and size of the scar-area have an important
bearing on the amount and extent of the eruption, and
consequently on the severity of the disease. Attention,
however, was only directed to counting the number of
vaccination scars, estimating their qualit}', or approximat-
ing their area, and verj' little has been done to measure
accurately this scar-area and to consider its relation
to severity and mortality at different age periods.

The cases of small-pox numbered 1,163, consisting of
943 vaccinated in infancy and 220 unvaccinated.

The method adopted was that of tabulating the age,
the presence or absence of vaccination scars, and in the
former case of measuring the area in square inches.

The cases were placed in ten age-groups, and arranged
in order to show the proportion of vaccinated and un-
vaccinated in each. These have been set out in Tables I
and //, where the extent and severity of the disease are
also revealed. The influence of vaccination on the mor-
tality will be first considered.

Influence of Vaccination on the Case-mortality.

Whilst there are several criteria of the severity of the
disease, such as extent of eruption, temperature, etc., the
one of most value is the case-mortality. When, therefore,
a comparison is made of the influence of vaccination
on the case-mortality of small-pox, it will be seen that
amongst the 943 cases which were vaccinated in infancy,
there were twenty-eight deaths, or 2-9 per cent, and
amongst the 220 unvaccinated cases there were sixty
deaths, or 272 per cent; 'that is, the ratio of deaths to
attacks is ten times as great in the unvaccinated as in
the vaccinated {see Table II, page 14).

These percentages are almost identical with Marson's
well-known figures, viz., about 8 per cent in those alleged
to be vaccinated with or without evidence, and 35-5 per
cent for the unvaccinated ; these figures are the result of
twenty-five years' (1835-60) observations on post-vaccinal
small-pox at the London Small-pox Hospital. Dr. Russell's
figures for Glasgow (1871-72) were 3 per cent for the
vaccinated and 30 per cent for the unvaccinated.

Dr. Woodward, dealing with the last twenty-five years
of the i8th century, when all the patients were un-
vaccinated, states that the death-rate was 32 per cent of
the admissions to the Small-pox Hospital. Dr. Gayton's
figures for the metropolitan hospitals showed, in the well

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and imperfectly vaccinated, a case-mortality of from 3 to g
per cent, whilst it reached over 40 per cent in the un-
vaccinated, and in various other places it was just as high.

The small-pox of the last decennium has been of a
fairly mild type. The question of age distribution in the
population attacked, and the country of origin of the
disease, may have an important influence in determining
the virulence of an epidemic.

On the Chart A (pages 16, 17) and in the accompany-
ing tables, the cases have been arranged into suitable age
periods, so as to show clearly the value of vaccination on
the mortality in passing from infancy to adult and old age.
An examination of the deaths recorded amongst the
vaccinated under each age-group reveals the interesting
fact that no death occurred until the 20-30 year group is
reached, and the case-mortality for this group is only
0"9 per cent. It will be observed, however, that the
percentage case-mortality amongst the vaccinated steadily
rises from this point onwards in life, but never exceeds
10 per cent.

On contrasting these figures with those amongst the
unvaccinated, we observe a striking difference. Under
2 years of age the deaths are 58 per cent of the cases
attacked, for 2-5 years 30'6 per cent, and the figure then
falls until 10-15 years, when it is 3-2 per cent.

This decrease may be attributed to the gradual
development of the natural resistance and recuperative
power of youth enabling the patient to recover from the
disease ; this may be compared with what is observed in
other infectious diseases. From adolescence onwards the
mortality in the unvaccinated gradually increases, until it
reaches 50 per cent at the periods from 40 years and
upwards. This high ratio of deaths to attacks amongst

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the unvaccinated, especially at the early and late periods
of life, compares with what is well known of this disease in
pre- vaccination days, viz., that the severity and mortality
lay heaviest on infants and young children under ten years
of age. The large excess of births and rapid accumulation
of susceptible persons in the growing manufacturing towns
afforded ample material for an epidemic to feed upon;
therefore the number of adults and old people who had
escaped the disease in pre-vaccination days was few.
At the present time, when an epidemic spreads over the
country, in addition to the unvaccinated children, the
disease also attacks those adults who have never been
vaccinated in their youth, and in addition, the power of
recovering from small-pox decreases as age advances.

The Influence of Vaccination on the Eruption, and
ON the Severity of the Disease.

The amount of eruption on the body of a patient
affected with small-pox always gives one an opportunity
to form an opinion of the severity and probable - fatality
of the case.

The eruption may be divided into five categories, and
commencing with the very mildest, these are as follows :
modified discrete, discrete, profuse discrete, semi-confluent,
and confluent. For purposes of easy examination they
have been grouped with the descriptive terms as
follows : —

A. — Modified discrete and discrete, representing the
mild types of the disease.

B. — Profuse discrete and semi-confluent ; a moderate
type of severity.

PLATE I

A IMILD AND MODIFIED CASE OF SMALL-POX

Patient well vaccinated in infancy, the scar area approximating one square inch.
Age twentv-five years. Note the mild character of the eruption, which is, as usual,
chiefly confined as regards distribution to the face and extremities. The usual
freedom of the triangle of the neck from eruption is to be noted.

PLATE J 11

WELL-MARKED CASE OF SMALL-POX OF SEVERE CHARACTER IN A MAN WHO
NEVER BEEN VACCINATED UNTIL AFTER INFECTION WITH SMALL-POX

Patient unvaccinated in infancy. Vaccinated for first time seven days before
onset. Age twenty-two years. Note the severity of tlie case, tlie size of the
pustules, and distribution of the eruption, more marked on face and extremities
than on body. The vaccination has been successful, and without doubt saved the
man's life; he recovered completely. Photo taken on ninth day of eruption.

C. — Confluejtt or very severe ; to this last category
have been added those in which death occurred.

There are therefore three types of severity, viz.,
A mild, B moderate, and C severe {see Plates I, II,
and III).

Let us examine the eruption and severity at different
ages, as it occurs in the natural disease, i.e., in the
imvaccinated {see Chart A, page i6).

An examination of the column under 0-2 years of age
shows that over 58 per cent of the cases at this age period
are found with the fatal kind of small-pox, 31 per cent with
the medium type, and only 10 per cent with the mild form
of the disease ; the same is also the case for the period 2-5
years, showing the marked incidence of the severe kind on
unvaccinated childhood.

Contrast in Chart A the severity of the disease and
mortality under 10 years of age in the unvaccinated with
the similar columns in the vaccinated.

The middle period of life has a lower percentage of
severe cases ; this may be explained by the higher resistance
of the body and power of recovery, which gradually increase
up to 30-35 years of age ; this natural resistance is well
shown in the unvaccinated in Chart A.

The number of cases of moderate severity continues
high in the unvaccinated throughout life, but as- age
advances, the very severe type again appears.

The dark-shaded portion in the chart indicates the
mortality limit amongst the severe cases ; and it will be
observed that from 10 years onwards to 40 years many
severe and confluent cases recover. Compare this with
the severe cases followed by death in children under
10 years and in old people, that is, at the extremes of
life.

I. Influence on the Extent of the Eruption.

The effect of vaccination is to reinforce the natural
immunity of the body. When it does not prevent the
onset of the disease, it may either influence the extent of
the eruption or modify the character of the individual
papules. Let us consider first the influence of vaccination
on the extent of the eruption. On contrasting in Tables I
and // and Chart A, the primarily vaccinated cases under
the different age-groups, a distinct series of facts will
become apparent. In the first place, there are no cases
recorded under 2 years*, and only seven cases under
5 years ; the latter, moreover, were exceedingly mild in
character and characterized by very sparse eruptions, a
few papules only appearing in isolated parts of the body.
Again, only three cases of moderate severity appear under
10 years of age, and of the severe type no cases are
recorded under 20 years. When the columns of vaccin-
ated persons in Table II are contrasted, it will be seen
that the percentages of persons with the different forms
of the disease are graduated : the highest percentages in
each age group are found to have the disease in a mild
form, the next highest in moderate form, and so on; the
most severe cases show the lowest percentage and only
appear after 25-30 years of age, and the deaths occurring
in this period are comparatively low.

On the total cases of all ages amongst the vaccinated,
the percentages are 727 of mild type, 237 moderate, and
only 3 '6 of a severe character.

The protection afforded by vaccination against attacks
of the disease is therefore well seen in this investigation,
where no cases of small-pox in the vaccinated are to be
found under 2 years of age* {see pages 13, 14, 16), that is,

* See footnote, page 31.

in the years immediately following upon the process of
vaccination.

II. Influence in Modifying the Character of the
Specific Eruption.

The eruption of unmodified small-pox usually passes
through a well-recognized series of changes.

The first appearance of the eruption takes place
approximately three days after the onset of symptoms, as
red spots about the size of a pin's head, first seen chiefly
on the forehead and wrists. They cannot be felt as distinct
spots above the skin, and disappear on pressure. Shortly
after, they swell into raised pink papules, fairly hard and
easily perceptible to the touch ; they grow in size and can
frequently be recognized as " shotty," but this depends on
their position in the skin and the tension of the contents
due to effused fluid. After a day or so, when they have
become, in typical cases, rounded and defined, vesiculation
develops, and at the beginning of the third day the papules
have become vesicular. These vesicles are loculated, and if
pricked, the clear contents will escape in small amount.
The loculation is due to trabeculae running through the
interior which divide the pock into several compartments.
These vesicles gradually become opaque or grey in colour,
and the contents become pustular ; this happens about the
sixth day of the eruption, and by the eighth, ninth, or
tenth day they begin to dry up, with the formation of
crusts. This is the typical course in all cases except
those of a severe or hsemorrhagic character. In cases
modified by vaccination, various interesting changes may
be demonstrated in the character of the eruption.

The following modifications in the eruption due to

vaccination have been noted in the series under examina-
tion.

1. The papules have been numerically few in number
and limited to isolated parts of the body. They have,
however, gone through the typical course of evolution.

2. The rash has been profuse, but the lesions were
superficially placed ; the vesicles or pustules were frequently
small or irregular in size, and owing to their superficial
position were unilocular, like vesicles in chicken-pox ; in
some cases they evolved quickly, and suppurated early and
imperfectly.

3. The papules, owing to wart-like masses of granula-
tion tissue formed at the base, appeared as raised fleshy
elevations.

4. A concurrent vaccination might cause rapid
inspissation of the pustules, the crusts dropping off early.

In' the accompanying Plate IV, the first type is well
illustrated ; the rash is very sparse, the papules passing
through the various typical stages as in natural small-
pox, attaining full size. The type described under
No. 2 is well shown in Plate V, where the rash is very
profuse, but the individual lesions are much smaller than
those occurring in natural small-pox, the pustules varying
in size from a pin's head to a pea within a small area ; they
are superficially placed in the skin, and the eruption has
passed through to suppuration quickly and imperfectly.
In this respect it is well known that the rapidity of evolution
of a papule varies with its size and the depth of its situation
in the skin, and the photos show the effect of the vaccination
in bringing about this condition.

Another type illustrated, Plate VI, shows a modified
eruption which is known under the name of " wart-pocks."
These pocks are chiefly found on the face, and consist of

PLATE IV

A MILD AND MODIFIED CASE OF SMALL-POX INFECTED. SIX DAYS
BEFORE BIRTH. FROM ITS MOTHER

The child was born in hospital and successfully vaccinated on the same day
Age fifteen days. Note the few and scattered papules on this infant, the modihed
character is due to the successful vaccination which was done six days before
onset of disease. Photo taken on the seventh day of eruption.

PLATE V

MODIFIED CASE OF SMALL-POX, SHOWING IN THIS CASE A NEVOID
CHARACTER OF A CONCURRENT VACCINATION

Patient vaccinated in infancy. Re-vaccinated oii the day of appearance of
eruption. A^e twenty-six years. ' In tins case of small pox the rash >s Profuse but
extremely modified, the papules vary much in size are superficially placed rnatur-
iuK rapidly and irregularly. (A) Superficially placed and rapidly maturing papules.
Photo taken on ninth day of rash.

PLATE VI

A WELL-MARKED CASE OF SMALL-POX, SHOWING CONDITION
OF "WART POCK ■'

This type of case, altliough somewhat repulsive in appearance, is nevertheless
fairlv mild m its character, and permanent disfigurement or pitting rarely follows.

PLATE VI I

SEVERE CASE OF SMALL-POX, NOT VACCINATED
BEFORE INFECTION.

Patient unvaccinated in infancy. Vaccinated on the day following the appear-
ance of the rasli. .^ge thirty-four years. Ttie case sliows the effect of a con-
current vaccination on the course of the disease, a rapid pustulation and drying up
of the rash. (A) Atypical vaccination scars with aborted vesicle and yellow crust.
The clear areas around each scar are not vesicles, but white or pinkish areas left
by the retraction of the scab. Photo taken on the thirteenth day of rash.

papules raised by the formation of wart-like masses of
granulation tissue; the papules have a fleshy base, and
frequently the suppurative process is shortened, the pocks
being surmounted by a yellow pustule about the size of a
pin's head, which soon dries up, pitting is rare.

[ Frequently, a vaccination when performed after the
date of infection, or even after the onset, has the effect of
hastening the maturation and desiccation of the pustules.y
For example, Plate VII shows a patient, un vaccinated in
infancy, who developed small-pox with a sudden and
violent onset and profuse rash. Vaccination was performed
on the day following the appearance of the rash, but in
spite of this it was thought the course of the disease would
prove to be severe. Suppuration set in about the usual
time. When the pustular stage ought to have reached its
height, however, and the patient would have been in a
most critical condition, the temperature fell, the pustules
at once began to inspissate and form crusts, and then
rapidly fell off. The patient was free from crusts in an
incredibly short time. This rapid passage through the
pustular and desiccation stages was undoubtedly due to
the vaccination.

Ricketts regards vaccination as having a double
effect on the course of the disease : one effect is an influ-
ence on the extent of the rash, or the numerical severity ;
the other is in the direction of modifying the eruption.
As age advances he regards these two faculties as waning
together, but " the protective influence against numicrical
severity goes quicker, and the faculty to cause an eruption
to be modified is retained for years after the other is
wholly lost."

These points are well illustrated in the series of
photographs which accompany this paper.

De-vaccination.

The length of the period of protection can be fairly
well gauged by an examination of the appended Tables.

The period will vary a good deal for each individual,
but from the figures given, the highest resistance lasts only
a short time. After a few years those who become
susceptible develop the disease only in a mild form, and
further on in years greater severity manifests itself in the
type of the disease, but no cases of severe and fatal small-
pox appear in this series of cases until over 20 years of age.
It is evident, then, that following a primary vaccination
in infancy, the period of greatest protection in childhood
probably does not cover more than three to five years,
and after this, the absolutely preventive efficiency of
vaccination rapidly diminishes, and cases of small-pox
begin to appear amongst the vaccinated. The power to
modify the disease, however, still continues to remain
considerable until adolescence, and even into later life,
as will be seen by comparing the severity and the
percentage case-mortality in different age-groups of
vaccinated and unvaccinated cases.
( The rapid loss of vaccinal immunity following on
primary vaccination in infancy is probably to be explained x
by the rapid changes going on during growth in childhood. y'
The experience of those who have done much vaccination
in adolescents or adults shows that the protection afforded
to adults by re-vaccination lasts much longer than the
same operation in children. It is well known that this
restored protection again diminishes, but much more

slowlyw

An instructive example of this gradual loss of pro-
tection was shown in six members of a family (a mother

and five children) admitted to hospital suffering from
small-pox. The disease attacked them all in varying
degrees of severity. They all showed evidence of having
been vaccinated in infancy : each of the children had only
one vaccination scar, of | square inch in area ; the mother
had three vaccination scars, each of the same size.

Case

Age

Number
of Scars.

Scar-area

Character of
Disease

Remarks

4 years

§ sq. inch

Modified
discrete,
very mild

Papules very few, not
over 7-8, and not
vesicular.

27..

ditto

ditto.

9 ,.

ditto

Papules few, more
numerous than in
cases I and 2, not
vesicular.

12 ,,

ditto

Modified
discrete,
mild

Papules very numer-
ous, became vesicular
but soon dried up.

ditto

ditto.

I J sq. inch

Discrete

Eruption more
marked than in the
children, and passed
through the charac-
teristic stages.

This series shows the gradual loss of the modifying
power in the vaccination as age advances, and it is interest-
ing as shown in the same family, the vaccination scar-area
being the same in each case except in the mother, whose
scar-areas were much larger, and therefore her protection
showed a proportionally larger degree of modifying power.
Where age has advanced sufficiently to ehminate the

previous vaccinal protection, it will be found that the
disease reverts to its original type, as seen in the
unvaccinated. In many cases, however, the immunity
conferred in infancy may persist in some degree until late
in life, especially in its power to modify the disease. This
gradual loss of immunity is well shown in the vaccinated,
in Chart A {page i6), where as age advances the mild cases
become fewer in number, and later in life the severe types
of the disease, with deaths, begin to appear.

PART 11.

AN ANALYSIS OF 943 CASES OF SMALL-POX (WITH

PRIMARY VACCINATION) IN RELATION TO

SCAR-AREA AND SEVERITY OF DISEASE.

The beneficial effects of vaccination are to be experienced
especially in those cases where the process has been carried
out in a thorough manner, and we may conclude that
where vaccine lymph has been inserted in several places
it is more effectual than when inserted in one place only,
i.e., the larger the local manufactory of immunity or the
greater the quantity of the specific material inserted, the
greater the degree of the resulting protection.

Accordingly, the amount of immunity may be reckoned
by the superficial area of the scar.

An analysis of the above-mentioned 943 cases of
small-pox, which had been primarily vaccinated, was
carried out to test the point. The scar-area was recorded
for each vaccinated case of small-pox on admission to
hospital, according to the method referred to in the circular
letter of the Local Government Board of England, issued
in 1902. The diagram (on page 28) represented the area
of the scars in square inches, and was used to estimate
it rapidly, and to record it. This method of recording
superficial area is a much better one for estimating the
relationship of immunity to mortality and severity, than
that of counting the number of scars, as was done in the
valuable series of Dr. Marson and others.

The scar-areas were arranged into age and severity
groups; an average scar-area was also obtained for each
age period ; this gi-ouping of scar-areas into severity and
age groups has proved a most important one, and some

V J

Scar-area Diagram of the Local Government Board.

new facts have come to hght regarding tlie changes which
scar-areas undergo.

A glance at the figures in Table III will illustrate
clearly the arrangement in relation to severity and age.

The severity groups are the same as those used in the
examination of the previous set of small-pox cases in
Part I.

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In the early years of life it is striking, as previously
stated, to find that under two years of age no cases of
small-pox are found amongst those who have had a primary
vaccination in infancy,* from 2-5 years only very mild
cases, and from 5-20 years no severe cases of small-pox, or
deaths, have occurred. ■ In the remaining years of life, it is
interesting to observe that in almost every age group the
mildest types of the disease (modified discrete and discrete)
are those with the largest average scar-area ; those with
moderate or severe types of the disease (profuse and semi-
confluent) have a slightly smaller scar-area, at least in
mid-age periods ; and in those with the most severe types
of small-pox, or where deaths have occurred, the scar-area is
the smallest (see scar-area diagram, page 32). It would be
well to note that it is a difficult matter to lay down a
standard of severity for each group of cases, especially
of the mildest types. The general impression created
by the extent of the eruption being the only guide, cases
on the border line are difficult to locate, and when the
cases in any group are comparatively few, the more diffi-
cult it is to attain absolute accuracy.

It is clearly evident, however, that the scar-area of
the vaccination bears an inverse relation to the character
of the eruption and intensity of the disease. An ex-
amination of Table IV, A, will show the average scar-
area for all the cases at each age-period. It is striking
to notice the gradual increase in this scar-area until 20-30
years, and following on this, a gradual decline in the size
of this area as years advance.

* I do not here include cases of small-pox in infants (see chart and
photographs at the end) who have been vaccinated for the first time after
infection with the disease, and have been in many cases bom in a small-pox
hospital. These are included amongst "concurrent cases," which are dealt
with in Part III. as a separate class.

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This point has proved of some interest, and an attempt
has been made to explain it. It was thought that in early
life, and up to 20 years, those persons who had larger
areas than those recorded escaped small-pox. As the
primary vaccinal immunity, however, gradually faded,
these persons came under the influence of the disease, and
the recorded scar-area of the small-pox cases increased.

This supposition, however, ought to hold good and
to extend into old age ; this it does not do, and it will
therefore not explain the steady fall which takes place
from 30 years onwards.

On reviewing the figures it becomes more probable
that the increase in the scar-area is due to stretching of
the scar tissue on growth of the body, reaching its height
at the period 20-30 years, and as age advances this scar
cicatrix begins gradually to atrophy and fade. This seems
clearly borne out by the figures, in the tables and in the
diagram opposite.*

In order to test this matter still further a measurement
was made of the scar-areas of a certain number of the
general population who have never had small-pox.

The persons whose measurements were taken were
those found in some of the infectious-disease hospitals,
where the majority were children ; a further series was
obtained in the Liverpool Workhouse, where persons of
middle and advanced age were examined.

In all, the scar-areas of 368 persons, who never had
smaU-pox, were measured. The figures in Table IV, B
{page 30), and the diagram opposite, show the result. It
will be evident that there is a gradual increase in scar-area

* The suggestion of this explanation was made by my colleague,
Dr. Stallybrass.

ill each age-period, from 25 square inch under 2 years
of age, to II square inch at 20-30 years of age: this is
the highest average reached ; the area then gradually falls
away in size until at 60 years it is '47 square inch.
This gradual increase until 20-30 years and then a gradual
decline is a matter of some importance, and is fuUy sub-
stantiated when we consider that in all, including small-
pox cases, the scar-areas of 1,311 persons have been
measured.

Another interesting point to observe is that the curve
formed by the average vaccination scar-area of the general
population which is shown on the attached diagram, is a
higher one at all age-periods than that obtained from those
who have been attacked by small-pox. This is another
point in favour of the value of large vaccination areas in
protecting the individual from the disease.

In many previous investigations on the influence of
scar-area on small-pox, the cases with the scar-areas of
approximately the same size have been taken and grouped,
and shown to be associated with varying degrees of
severity ; but no account seems to have been taken of the
age of the patients, nor was the interesting fact realized
that the scar-area in the individual varies at different
periods of life. In future comparisons t^is point will have
to receive more consideration.

PART III.

OBSERVATIONS ON THE INTERACTION OF
CONCURRENT VARIOLA AND VACCINIA.

It has been abundantlj^ shown by the experiments of
Thiele and Ceely, and more recently by Klein and Copeman,
that cow-pox or vaccinia may be considered as an attenuated
descendant of small-pox ; and in connection with this close
relationship, if not absolute identity, of these two affec-
tions, the examination of the following series of 75 cases
of smaU-pox with a concurrent vaccination will prove of
interest. The cases have been collected during the past
ten years in the City and Port of Liverpool. Many of
them were persons who were landed incubating or suffering
from the disease, and were removed to the Port Isolation
Hospital; these were chiefly cattle-men from Boston, who
landed incubating small-pox during the severe outbreak
in that city in 1902-3.

The cases may be examined in the light of the relative
effects produced on one another by each of these condi-
tions : (i) As regards the success of the vaccination
when performed subsequently to infection with small-pox ;
and (2) As regards the effect of the vaccination on the
course and severity of the disease. Cases of concurrent
variola and vaccinia have rarely been given the prominence
which they deserve, and it was with this object that the
present series was collected. The series, then, gives
information of the effect of vaccination or re-vaccination

performed after exposure to infection and running con-
currently with the course of the disease.

The Success of the Vaccination.

The success of the process may first be considered,
and the series may be conveniently divided into two
groups, viz. : (i) Those who have never been vaccinated
until infected with small-pox, Chart B {page 37) ; (2) Those
who have been primarily vaccinated in infancy, Chart C.
{page 38).

On examining the charts it will be seen that the
period of twelve days has been taken as the duration of
the incubation period : this has been found to be prac-
tically correct for all the cases; they were all carefully
investigated both as to the symptoms of onset and initial
rash, and found to correspond to the period set forth in
the charts.

It cannot be disputed that possibly cases may occur
with a day or so longer or shorter incubation period, but
very few of this sort can be quoted as evidence for an
incubation period other than that stated. The average
generally accepted and acted on for public health adminis-
tration is twelve days, a period which has been found to
work out well in practice, the rash appearing about three
days after initial symptoms.

The first point to notice in connection with those
cases is that all have been exposed to the infection of
small-pox, and all with two exceptions {see Chart B),
have contracted and developed signs of the disease. These
two exceptions were cases of children born in hospital of
variolous mothers, vaccinated within 24 hours of birth,
and were under daily observation {see Plate VIII).

A few papules
A few papules
Papules few and scattered
A few papules — face, arms,
[legs. &c.

Very few papules

Death

Death
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The cases have been set out showing those vaccinated
and re- vaccinated on different days : first, during the period
of incubation, and second, after the onset of symptoms,
and even until three days after the rash had appeared.
It is unnecessary to say that vaccination efficiently per-
formed in susceptible people before exposure to infection of
small-pox will, almost without exception, prove successful,
and will protect the individual from developing any
symptoms or signs of the disease.

Vaccination during Incubation. — On examining the
charts it will be found that all the vaccinations and re-
vaccinations have been successful if performed during the
incubation period and even up to the day of onset of sym-
ptoms. When the term "successful" is used, it must be
understood that the phenomena at the site went through
the typical and normal course of human vaccination.
These phenomena may be shortly described as follows :
a sUght inflammatory reaction may appear at the site, but
nothing of moment occurs until the end of the third day,
when firm, fiat, elevated papules appear at the site of the
operation ; these become surrounded by a halo of hyper-
aemia. Vesicles appear on the fifth or sixth day, and are
especially marked at the periphery. These are filled with
clear lymph, and the zone of hypersemia has increased,
with acute swelling ; the vaccination is red and firm, and
the axillary glands may be swollen. Cloudiness begins to
appear in the vesicles on the eighth day, and subsequently
they become opaque and yellow. The height of the
vaccination is reached on the ninth or tenth day, and from
this date there are signs of rapid desiccation. The changes
most characteristic of vaccination are found during the
third, fourth, fifth, and sixth days.

The successful vaccinations and re-vaccinations

recorded in the charts were therefore more or less of the
above-described characters, and they all showed the
characteristic ring or vesicle situated on a papule and
going on to suppuration and desiccation. {See Plates IX
and X.)

Vaccination after onset of the disease. — -The operations
performed subsequently to the onset of symptoms were
unsuccessful {see Plates XI, and XI I). The papule did not
reach its typical character, the areola may not have
developed and vesicles did not appear, or the vaccine
pocks developed a nsevoid character or appeared stunted
in development, and rapidly dried up. It must be granted,
however, that in some of the cases the organisms introduced
into the system may have had some modifying effect on
the course of the disease, although no typical reaction
occurred. This point will be referred to later. In other
cases, and notably in those vaccinated late in the disease,
no reaction appeared at the site, or simply a slight trau-
matic reaction occurred. It will be well to mention at
this point, that fallacious conclusions may be drawn from
the appearance of the vaccination area under the following
conditions. It is well known that an especially abundant
eruption is not infrequently observed on parts of the body
which, before the eruption appears, have been affected
by mechanical or inflammatory irritation {see Plate XIII).
Such areas of eruption are sharply marked off, and take on
strikingly the form of the area of irritation, e.g., a patient
who has been previously carrying heavy bags on his back
will show a more profuse eruption on his shoulders, or
the irritation in the front of the neck caused by a collar
stud will cause a little crop of vesicles to appear at this
point. Other examples might be mentioned, such as an
eruption round the thigh where a garter has caused pressure.

PLATE VIII

MOTHER SUFFERING FROM SMALL-POX NURSING HER
SUCCESSFULLY VACCINATED BABY.

Mother aged twenty-five years. Vaccinated in infancy. Baby born in liospital
and successfully vaccinated on the following day. No signs or symptoms of
small-pox appeared in the child, which was nursed by the mother throughout her
own illness in hospital, and discharged after six weeks, (A) Infant's successful
vaccination. Photo taken on the ninth day of the vaccination.

PLATE IX

A VERY MILD AND MODIFIED CASE OF SMALL-POX

Patient vaccinated for the fir^ time seven days before onset of symptoms.
Age seven years. The successful vaccination has modified exceedingly the disease,
so that the papules are comparatively few in number. This boy was infected by
his sister, who was unvaccinated, and had a most severe attack of small-pox.
Photo taken on the sixth dav of rash.

PLATE X

A MODIFIED CASE OF SMALL-POX

Patient vaccinated in nilancv. Ke-\accinatecl lour days before onset of disease.
Age twenty-six years. This patient shows a successful re -vaccination which is
typical in appearance.

PLATE XI

A MILD AND MODIFIED CASE OF SMALL-POX

Patient vaccinated in infancy. Ke-vaccinated on tlie day after onset of
symptoms. Age twenty-four years. This patient shows a vaccination which is
atypical in character.

PLA TE XII

SEVERE ATTACK OF SMALL-POX IN A PERSON WITHOUT
PRIMARY VACCINATION IN INFANCY

Patient iinvaccinated in inlancy. Vaccinated lur first time un the fourth day
of the disease. Age twenty-seven years. The plate shows that the eruption, as
shown on the upper arm, was very profuse over the body ; the vaccination having
been performed rather late was atypical and naevoid in character. Photo taken
three weeks after the appearance of the rash.

PLATE XIII

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A VERY MODIFIED CASE OF SMALL-POX

Infantile vaccination did not take. Re-\'accinated successfully six days before
onset. Age tweh'e years. This case is interesting as showing that the inflam-
matory areola around the vaccination area has determined a numerous crop (A) of
small-pox vesicles to appear. The rash is well marked and confined more particu-
larly to the face. Photo taken on the sixth day of the rash.

PLATE XIV

A CASE OF SMALL-POX OF MODERATE SEVERITY

The patient was a Kiissian inimi{,'rant, and had been very poorly vaccinated in
infancy, the scar-area oiilv appi cixiinatinf,' one-tenth square inch. He remained
critically ill for a long timr, luit ultimately recovered. Aged seventeen years.
A scratch on the right hand caused by the patient breaking a pane of glass has
determined a confluent crop of papules to develop on each side of the scratch.
(A) Confluent crop of vesicles at scratch.

PLATE XV

A MILD AND MODIFIED CASE OF SMALL-POX

The patient was \accinated n\ iiilancy. Re-vaccinated witliout result five days
after onset of the disease. Age twenty -five years. .\ confluent eruption is seen on
tlie foreliead, due to spirit compress used by the patient to reUeve headache.
The patient was vaccinated five days after onset of the disease without any local
result. (A) Unsuccessful attempt at vaccination. Photo taken on fifth day of
the rash.

PLATE 11

A CASE OF SMALL-POX OF MODERATE SEVERITY

Patient vaccinated in infancy. Ke-\accinated successfully six days before erup-
tion appeared. Age twenty-four years. Note that in this case the rash is more
profuse than in Plate I , but the distribution is the same. The anterior triangle of
neck is relatively free. The re-vaccination is well shown, and there is a charac-
teristic crop of small-pox vesicles situated on the inflammatory areola around the
vaccination site. Photo taken on fifth day of rash.

PLATE XVI

^^^^^^^^^t^^

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A SEVERE CASE OF SMALL-POX

The patient was vaccinated in infancy. Re-vaccinated without result five days
after onset of disease. .\ge thirty-five years. The case shows that the disease may
become very severe in those who liave lost immunity with advancing years: this
patient is ten years older than that shown in Plate XV. The result of vaccina-
tion was atypical and of a nsevoid character. Around the areas are irregular rings
of confluent small-po.\ vesicles and pustules, which give an erroneous appearance
of success. Photo taken on the eighth day of the eruption.

or a confluent eruption on each side of a scratch on the
hand {see Plate XIV). Similar phenomena can be seen
after chemical or other irritation {see Plate XV).

When a vaccination has been performed, therefore,
from the day of onset onwards until the rash appears, the
inflammation and irritation due to the operation and the
slight local reaction which occurs may cause a crop of
small-pox vesicles to appear around the area. This is
especially the case in severe or confluent small-pox, but
may be also seen when the rash is very sparse on the rest
of the body. These vesicles, especially in severe cases,
may coalesce so as to form a ring around the vaccination
site, and give rise to a false appearance of success of the
operation {see Plates XVI and XVII). Many cases,
therefore, said to be successfully vaccinated, are really due
to coalescence of small-pox vesicles and pustules around
the area of the vaccination. This, I am convinced, is the
case ; it is only likely, however, to give rise to doubt in
cases of severe or confluent small-pox where the eruption
is profuse.

Clinical Society's Report. — These observations were
completed, when attention was drawn to a report, published
in 1878, of a Committee of the Clinical Society of London,
formed to investigate the periods of incubation, contagious-
ness, etc., of small-pox In this report there are twenty-
two cases of concurrent variola and vaccination recorded
by Dr. Birdwood, of the Metropolitan Asylums Board's
Hospital. These cases are incomplete in their details, but
I have taken twenty of them which can fairly well be used
in comparison. These have been arranged in the same
type of chart as that of the present paper, and it is
surprising to find a very close agreement {Chart D, page 42).

It will therefore be abundantly evident from the

Malaise, Fever, &c. No Rash

Apparent success due to irrita-
tion and inflammation at site
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charts and photographs that the operation of vaccination
performed at any time during the incubation period will
be successful. This may be true even during the first
period of onset, but if carried out subsequently to the
initial symptoms, the vaccination will not be successful or
typical in its appearance. Dr. Birdwood states that he
has " only found one vaccination which was successful if
vaccinated on the day of eruption or after." In my opinion,
and for the reasons which have been given, the case was
probably not a successful one, the appearance of success
having been given by the coalescence in a confluent case
of the vesicles and pustules around the inflammatory zone
of vaccination. In the same report, Dr. Colclough, who
was at that time Assistant Medical Officer at the hospital
ships, in a note states, " In the few instances in which I
have vaccinated patients on their admission, when the
eruption has been in the macular or papular stages, the
re- vaccination has failed, and the reports of over fifty cases
of re-vaccinations (taken from the case books), in various
stages of eruption, coincide with my few instances."

I have often heard the statement made by medical
men, that when persons have been vaccinated and the
operation is not proving successful, there is a likelihood
they will develop small-pox, or that these cases ought to
be watched and isolated. In my opinion it is in cases
recently vaccinated which show evidences that the opera-
tion will probably be successful, and where there is low
immunity, that small-pox is likely to develop ; these
cases require to be kept under surveillance. Some time
ago, a vessel arrived in Liverpool having had a case of
smaU-pox on the voyage ; the man died and was buried at
sea five days before reaching Liverpool. All the crew were
vaccinated on arrival ; one of them, who assisted in burying

this man, developed a very mild rash of small-pox ten days
after vaccination and the arrival of the ship ; his vaccina-
tion had taken in three places, and showed typical vesicles
and other associated signs. Therefore, assuming that the
vaccinations have been properly performed with active
lymph, the cases to be watched more particularly are those
which show signs of the vaccination " taking."

Influence of Concurrent Vaccination on the
Course of the Disease.

Another aspect of the subject may now be studied
with advantage, namely, the influence of this vaccination
on the course and severity of the disease {see Charts B, C,
and D).

The degrees of severity have been classified for con-
venience into three groups : Column i represents a mild
attack of the disease ; Column 2 a moderate or severe attack ;
and the very severe group is recorded under Column 3 :
this group also includes deaths, but these are shown
individually in the body of the table.

Chart B. — On an examination of the thirty cases
without a primary vaccination in Chart B, it will be seen
that of Cases i to 5, vaccinated within the first three
days of infection, two developed no symptoms or signs of
the disease, whilst three had an exceedingly mild attack
after an initial malaise. In these latter onlj' a few papules
appeared, which never became vesicles, but simply died
away ; in these aborted cases the small-pox had just over-
come the protective effect of the vaccination.

Tracing the cases further on in the disease, we find
that the type becomes more or less severe, according to
individual susceptibility, until we come to those of

moderate severity, vaccinated from the seventh day of
infection up to the onset ; following on this the cases
vaccinated after the onset of the disease will be seen to
have been of the very severe t^'pe, three of them ending
fatally, showing that cases vaccinated at the stage of onset
and after the rash has appeared, have much less chance of
benefiting by the vaccination.

Chart C. — If attention be now turned to Chart C,
showing forty-five cases of small-pox with a primary
vaccination in infancy, it is of interest to find that in this
group the effect of the primary vaccination is shown on the
course of the disease : the primary vaccination along with
the re-vaccination performed concurrently has greatly
assisted in modifying the severity of the disease.

Further, it will be noticed that in this chart of cases
which show a primary vaccination, there are no cases found
vaccinated on the day of infection or on the first three days
following. This may be accounted for by the fact that the
double vaccination, i.e., primary and re- vaccination, has
prevented the onset of symptoms or appearance of rash in
persons re-vaccinated on these days, and therefore I have
been unable to obtain small-pox cases to place on the
chart in the position corresponding to these days ; this
view is also supported by the chart of Dr. Birdwood's
cases. It may be remarked, however, that the number
of cases is smaU to draw such final conclusions ; still, I
draw attention to the fact as being one of probably some
importance from an administrative standpoint.

On examining the cases re-vaccinated before the onset
of symptoms, it will be seen that in nearly all the disease
was of a mild or very mild type. Taking this portion, i.e.,
during incubation period, of the series in Chart C, there
are only four cases out of twenty-seven in which the

eruption may be considered as of moderate or severe
character.

The cases vaccinated after the onset of the disease,
and subsequently to the appearance of the rash, showed a
more pronounced type ; in this case most of the patients
had the disease in a moderate or severe form.

When it is stated that the vaccination or re- vaccination
was unsuccessful as an operation, it must not be understood
that the modified organisms implanted in the system did
not exercise any appreciable modifying effect. Case No. 28
amongst the unvaccinated (Chart B) illustrates this point.
A lady, unvaccinated in infancy, contracted small-pox
abroad, and was vaccinated one day after the appearance
of the rash ; a slight traumatic reaction occurred at the
site of vaccination, with ill-defined papule and aborted
vesicle, forming a yellow crust, which was quite atypical.
The case passed through a severe attack ; towards the
twelfth to fourteenth day of the disease, however, when the
suppurative stage ought to have been at its height, it was
surprising to find the pustules rapidly drying and falling
off, so that within a day or so they had entirely gone ; the
resulting scars were totally absent, and only marked staining
remained, which disappeared under a year, and no trace of
the disease can now be seen after some years. The case
was, to my mind, a convincing proof of the value of
vaccination done subsequently to onset of symptoms, and
the operation ought therefore to be performed on all cases
admitted to hospital. Other cases, not so striking, can be
quoted.

The remarkable antagonism of these two diseases can
only be explained by a consideration of the question of
immunity or concurrent immunities. It may suffice to
say that in small-pox with a concurrent vaccination, it is a

race between the virulent and the modified organisms ;
the less virulent and the more saprophytic forms grow
faster and produce immunity more quickly than the
more virulent ones. Protection is not acquired at any
particular time, but there is a gradual accumulation of
immunity in the blood, which usually shows itself to be
completed by the beginning of the second week after
vaccination.

It would seem from an examination of the charts, that
nine days after vaccination is the period required to give
real evidence of the increasing protection against small-pox.

It is therefore evident that the intensity of the disease
bears an inverse ratio to the period of vaccination ; the
later the disease appears after vaccination, the more
opportunity for the vaccination to be successful and develop
its counteracting immunity; when the small-pox appears
early in the course of a vaccination, the more severe is
the course of the disease.

On referring to Chart B of unvaccinated cases, it will
be seen that cases of small-pox vaccinated within three
days after infection will develop very slight or no sym-
ptoms of small-pox ; and a reference to Chart C shows no
cases occurring within the first three days. One may
safely infer, therefore, that vaccinations performed within
the first three days of infection in persons with a primary
vaccination will not develop small-pox, and in those who
are unvaccinated the chances are that the disease will not
develop ; or, in other words, vaccination requires nine
days to develop an immunity which will absolutely
prevent or minimise an attack of small-pox.

Concurrent Cases amongst Infants.

An instructive series of concurrent cases is shown in
the following Chart E, with its accompanying photographs.
The series sets out in tabular form seven cases of small-pox
in infants with concurrent vaccination. The majority of
these were born in hospital of variolous mothers, and
vaccinated within a few days of infection ; two are shown
to have been infected in utero.

It will be seen that Cases i and 2 [Plates XVIII and
XIX), infected with small-pox on the da}^ of birth and
the day following respectively, were vaccinated within
twenty-four hours, with entire absence of development
of any symptoms or signs of the disease ; and the
mothers continued to nurse these children until they
were convalescent and discharged ; in these cases the
vaccinations were entirely successful and absolute pro-
tection was afforded.

Cases 3 and 4 (Plates XX and XXI) were vaccin-
ated later in the incubation period of the disease. Case 3
was vaccinated at the end of the third day of incubation,
and had a very mild attack, as illustrated in the photo-
graph. The eruption was very sparse and scattered, and
the individual papules rapidly passed through the pre-
liminary stages to pustulation ; this is one of the charac-
teristic effects of vaccination. Case 4 was vaccinated on
the fourth day of incubation, and had a very mild attack.

Case 5 {Plate XXII) was vaccinated on the fifth day
of incubation, the day following its birth, and showed
a more profuse eruption of small-pox. This baby was
infected in utero. The mother's rash appeared on
December 12th, while the child's eruption appeared on
December 27th, exactly fifteen days later.

Case 6 (Plate XXIII), four months old, and un-
vaccinated, was infected with small-pox on March 30th ;
owing to various circumstances in connection with the
illness of the mother and consequent delay in the
reporting of the case, the baby was not vaccinated
until the eighth day after infection; the eruption was
profuse, but complete recovery took place.

Case 7 was a baby infected on February 28th in utero.
The mother's rash appeared on that day; the child was
born on March 6th and vaccinated on March gth. The
disease was of very severe type and death ensued. The
vaccination in this case was carried out too late to have
an opportunity of neutralizing or modifying the course of
the small-pox.

Without undue repetition of perfectly obvious facts,
it will not be out of place to again point out that the
non-development of small-pox or its extraordinarily mild
character in those infants of the above series which were
vaccinated in good time, contrasts markedly with what is
shown in Chart A {page 16), as occurring amongst
unvaccinated children, where a 50 per cent mortality is
shown as a result of the neglect of this obvious precaution.

Fortunately it has been possible to insert two plates
{XXIV and XXV), which will bear out the above obser-
vation and serve as contrasts with the foregoing series.

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PLATE XVII

A SEVERE CASE OF SMALL-POX, UNVACCINATED IN INFANCY

The patient was vaccinated for the first time unsuccessfully three days after
onset of symptoms and after the appearance of the rash. Age forty-three years.
The result of the vaccination has been unsuccessful, and the appearance of the
vaccination areas compares with Plate XVI. Photo taken on the sixth day of
the eruption.

PLATE XV 1 11

l.-A CHILD SUCCESSFULLY VACCINATED ON THE DAY OF BIRTH
AND NURSED BY ITS MOTHER. WHO HAD SMALL-POX. THROUGH-
OUT HER ILLNESS OF SIX WEEKS IN A SMALL-POX HOSPITAL

Child born January 15th, vaccinated successfullv on January 16th. Mother
developed small-pox rash on January 16th, and nursed her child in hospital until
discharged. No development occurred in the child.

PLA TE XIX

-MOTHER SUFFERING FROM SMALL-POX NURSING HER
SUCCESSFULLY VACCINATED BABY

Mother aged twenty-five years. Vaccinated in infancy. Baby born in hospital
and successfully vaccinated on the following day. No signs or symptoms of
small-pox appeared in the child, which was nursed by the mother throughout her
own illness in hospital, and discharged after si.\ weeks. (A) Infant's successful
vaccination. Photo taken on the ninth day of the vaccination.

PLATE XX.

-AN EXCEEDINGLY MILD AND MODIFIED ATTACK
OF SMALL-POX

Child born April I'Jth, vaccinated successfully April -!ind, three days after
infection. Mother developed small-pox rash on April 19th, and nursed the child
throughout her illness. The baby developed a small number (twenty) of small-
pox papules scattered on its body. Photo taken on the third day of the rash.

PLATE XXI

Case 4— A VERY MILD AND MODIFIED CASE OF SMALL-POX

Child aged three months, was vaccinated successfully four days after infection
with small-pox, i.e., eight days before onset. The child developed a very mild
attack of small-pox; not more than eight or nine papules on the face, and about
twenty on the body.

PLATE XXII

-ANOTHER CASE OF MILD SMALL-POX IN AN INFANT
SUCCESSFULLY VACCINATED BEFORE ONSET

Child aged fifteen days, born on December 16th, and successfully vaccinated
five days after infection from the mother, whose rash appeared on December 12th.
The child de\'eloped a mild attack of small-pox with sparse eruption. It will be
noticed that the later the day of vaccination after infection, the more severe the
character of the disease. Compare Plates A'.V, XXI, and XXHl. Photo taken
on sixth day of the rash.

PLATE XXIII

.-ANOTHER CHILD. SHOWING A MILD AND MODIFIED ATTACK OF
SMALL-POX. AND VACCINATED FOUR DAYS BEFORE ONSET

Child aged four months, was successfully vaccinated eight days after infection
with small-pox. The patient developed a modified attack of small-pox, but the
eruption was much more numerous and pronounced, and papules of larger size,
than in any of the previous cases. Photo taken on eighth day of the rash.

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Conclusions.
The following conclusions may be drawn from the

Part I :—

{a). That the case mortality in the natural disease,
i.e., in the un vaccinated, which ranges from
approximately 25 to 40 per cent, has been
reduced by the power of vaccination to about
3 per cent in those who have been well
vaccinated.

[b). That in the unvaccinated, persons at the extremes
of life, mainly children under 10 years of age
and old people, are those who suffer most, the
case mortality reaching as high as 50 per cent.
In the previously vaccinated, no cases are
recorded occurring under three years of age;
under twenty years of age no deaths are
recorded, but as age advances the vaccination
gradually loses its protective and modifying
power.

(c). That even when, owing to age, and consequent
gradual loss of vaccinal immunity, vaccination
' is unable to stop the development of the disease,
it may modify the extent and character of the
eruption to such a degree as to make it so
exceedingly mild that in many instances the
disease may be undetected.
\ 7

Pari II :—

[d). That the scar-area of vaccination has an important
bearing on the severity of the disease ; the
larger the area, the milder the character of the
disease.

[e). That the vaccination scar-area gets larger as age
advances until the 20-30 years age-period is
reached ; it then gradually becomes smaller,
in all probabiUty owing to atrophy of the scar
tissues.

Part III :—

(/). That vaccination performed subsequentlj^ to
infection with small-pox and up to the date of
onset of symptoms will " take " and pass
through its typical course.

(g). That protection is afforded against small-pox by
vaccination when performed within three days
after infection, but this may not be absolute in
cases vaccinated for the first time ; the course
of the disease, however, will be exceedingly
mild.

{h). That there is abundant evidence of the value of
vaccination in mitigating the severity of the
disease when performed at any time after
infection up to date of onset, and even after-
wards.

>-■

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